The new destroyer escort conducted shakedown training off Bermuda before departing Hampton Ronds .S June 1944 for the Pacific. Sailing via the Panama Canal, she arrived Pearl Harbor 28 June and engaged in convoy and training operations during July. John C. Butler then departed Pearl Harbor 9 August screening transports bound for the invasion of the Palaus. After seeing them safely to Tulagi, the ship operated with escort carriers out of Manus on preinvasion strikes. Two islands wanted as advance bases for the long-awaited move into the Philippines, Morotai and Peliliu, were stormed 15 September; and John C. Butler provided antisubmarine and antiaircraft protection for the supporting carriers. Returning to Manus 30 September, she replenished in preparation for the Leyte operation in October.

The escort vessel sailed with Rear Admiral Oftsie's escort carrier group 12 October to provide air cover for the massive movement of transports into Leyte Gulf. After the initial landings, the three carrier groups, soon to become famous by their radio code names, "Taffy 1," "Taffy 2," and "Taffy 3," took station east of the Philippines to lend close air support.

The Japanese fleet was closing the Philippines in a last attempt to annihilate the invasion force, with heavy ships designated to break into Leyte Gulf from north and south, and a diversionary fleet of earriers to draw Halsey off to the North. In the first two actions of the massive Battle for Leyte Gulf which ensued, the Battles of Sibuyan Sea and Surigao Strait, the Japanese were badly mauled. But Admiral Kurita's Center Force still transited San Bernardino Strait the night of 24-25 October and just after sunrise bore down on the relatively unprotected "Taffy 3," including John C. Butler.

The 2-hour battle off Samar which followed has taken~h rightful place among the most memorable actions in naval history. The slow escort carriers launched all planes to attack the Japanese cruisers and battleships, and Joh~z C. Butler and her sisters laid heavy smoke to confuse enemy hatteries. A rain squall provided cover for a turn to the south, and just after 0730 the destroyers began their gallant torpedo attacks against great odds. Johnston, Hoel, IIeermann, and escort Samuel B. Roberts made closein attacks on cruisers and battleships, forcing them to zig-zag, while aircraft made continuous attacks. Soon after this first attack, John C. Butler turned from the carriers to launch her remaining torpedoes, then exchanged gunfire with a heavy cruiser. The destroyer escort continued to fire and dodge heavy-caliber flre until dangerously low on ammunition, then returned to the carrier formation to provide smoke coverage. Admiral C. A. F. Sprague, commander of Taffy 3, later described the next surprising development: "At 0925 my mind was occupied with dodging torpedoes when near the bridge I heard one of the signalmen yell, '. . . dammit, boys, they're getting away!' I could not believe my eyes, but it looked as if the whole Japanese fleet was indeed retiring.... At best, I had expected to be swimming by this time." The Japanese, damaged and fearing heavier air attack, had indeed reversed course. Though the escort carriers lost two of their number and three escorts their valiant fight had stopped the Japanese from attacking the transports in Leyte Gulf.

After rescuing survivors from St. Lo, John C. Butler escorted the surviving carriers of "Taffy 3" via Manus

to Pearl Harbor, then returned to Manus 17 December. Departing with escort carriers 31 December, she protected amphibious transports steaming to the invasion of Luzon. During the voyage through the South China Sea, the ships encountered and drove off determined kamikaze nttacks. On the evening of 8 January 1945, John C. Butler and other escorts splashed several kamikazes. She op erated off Lingayen Gulf from 9 to 17 January and screened carriers during massive strikes in support of ground operations. Departing the Luzon coast, she arrived Ulithi 23 January to prepare for the next important amphibious landing—Iwo Jima.

Tho veteran destroyer escort took part in rehearsals in the Marianas, and arrived off Iwo 19 Iebruary with an escort carrier group. She again fought off a severe air attack 21 February. She remained on duty off Iwo Jima until 9 March 1945, when she sailed for Ulithi, having helped to win another important island air base for the eventual attack on Japan.

Okinawa was to be the site of the last and largest of the Pacific amphibious assaults. John a. Butler sailed 26 March with transports; and, as the troops stormed ashore 1 April, she resumed her now-familiar screening duties with carrier groups. As the Japanese launched fruitloss suicide attacks, the ship escorted carriers intO Kerama Retto, rescued downed pilots, and ferried men and material. Transferred to dangerous outer picket duty north of Ie Shima 20 May, she was attacked by six kamikazes just before sunset. Skillful gunnery accounted for five of the attackers, and John C. Butler sustained damage only to her mast and antennas. She sailed 27 May for repairs in the Philippines.

The ship returned to Okinawa with a convoy 4 July and spent the last month of the long war on convoy duty between that island and the Pacific advance bases. She returned to San Pedro 23 November and decommissioned 26 June 1946, joining the Pacific Reserve Fleet at San Diego.

With the outbreak of the Korean conflict in June 1950, .John a. Butler recommissioned 27 December 1950. Following shakedown, she was assigned to 11th Naval District for the important job of training naval reservists on short sea cruises. Thus, she helped maintain highly trained offlcers and men to meet the Navy's cold war commitments. In addition to reserve cruises, she took part in the training program of Fleet Sonar School, San Diego. She decommissioned 18 December 1957 and reentered the Reserve Fleet, San Diego, where she remains.

John C. Butler received five battle stars for World War II service, and was awarded the Presidential Unit Citation for her part in the Battle off Samar.